linux-kernel - Re: [PATCH 1/4] firmware: Refactoring for splitting user-mode helper code

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Message-ID: <CACVXFVN9JNe6US655hh3cNpKyJFdWrLEYOOOdnk97_5bFmZYxw@mail.gmail.com>
Date:	Wed, 30 Jan 2013 18:25:20 +0800
From:	Ming Lei <ming.lei@...onical.com>
To:	Takashi Iwai <tiwai@...e.de>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] firmware: Refactoring for splitting user-mode helper code

On Wed, Jan 30, 2013 at 3:17 PM, Takashi Iwai <tiwai@...e.de> wrote:
>> The above usermodehelper_read_lock thing may be a functional change,
>> and looks not what you claimed in commit log, :-). The lock is currently held in
>> direct loading case, but your patch change the rule. Without holding the lock,
>> request_firmware() may touch filesystem / storage too early during
>> kernel boot or system resume in direct loading case.
>
> Does it really happen in a real scenario?

Some crazy drivers might call request_firmware inside resume callback,
with usermodehelper_read_lock, we can find the mistake easily and log it.

>
> If so, using usermode helper lock for that purpose sounds like an
> abuse to be fixed differently or replaced with a better one.

Might be, but looks not good to introduce this change in a code
refactoring patch. Or you can do it in another patch for discussion
if you have better way to handle the situation.


Thanks,
--
Ming Lei
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